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Giving Sight by Therapy With Genes

By the time Corey Haas was 7, the retinal disease he was born with had already stolen much of his vision. “He always clung to me or my wife,” said Corey’s father, Ethan Haas.

The boy relied on a cane and adults to guide him, and, unable to see blackboard writing, sat in back with a teacher’s aide, large-type computer screen and materials in Braille.

Legally blind, Corey was expected eventually to lose all sight. Then, 13 months ago, after his eighth birthday, he underwent an experimental gene therapy procedure, receiving an injection in his left eye.

His vision in that eye improved quickly. Now 9, Corey plays Little League baseball, drives go-carts, navigates wooded trails near his home in Hadley, N.Y., and reads the blackboard in class. “It’s gotten, like, really better,” he said.

Experts in vision problems say that while it is unclear how many visually impaired people gene therapy could help, they consider the research promising for some types of blinding diseases, and an achievement for gene therapy, which has had many setbacks.

The study, reported in the journal Lancet, involved five children and seven adults, from Belgium, Italy and the United states, with a type of Leber’s congenital amaurosis, rare but serious congenital retinal diseases.

The researchers injected into the eyes of the patients a virus with the normal version of the gene RPE65 inserted into its genome. When the virus invaded the light-sensing cells in the eye and inserted its own DNA into the cells’ DNA, the crucial human gene was included.

Starting at about two weeks, “all 12 had significant improvement,” said Stephen Rose, chief research officer at the Foundation Fighting Blindness, which helped finance the study. That meant the inserted gene was functioning. “You’re not returning 20-20 vision, let’s be real,” Dr. Rose said, “but you’re returning a tremendous amount of vision.”

Dr. Jean Bennett, an ophthalmology professor at University of Pennsylvania who was a leader of the study, said participants could “read signs or see numbers on their cellphones, stripes on their clothes, patterns on furniture, wood on a violin or marble on a table.” Some read several more lines on eye charts.

Children improved the most, perhaps because fewer photoreceptors had decayed. But even the oldest patient, Tami Morehouse, 44, who was sometimes housebound, now walks to meet her children coming from school and “saw her daughter hit a home run,” Dr. Bennett said.

In a burst of new research on restoring sight, gene therapy is one of the methods closest to achieving results, but it will not help everyone because some eye diseases destroy photoreceptor cells, which are crucial for allowing gene therapy to work. Also, specific genes must be identified for different strains of diseases.

“Gene therapy is great, but it’s going to work only when patients have viable photoreceptor cells,” said Dr. Gerald Chader, chief scientific officer at Doheny Retina Institute in Los Angeles, who was not involved in the study. “There’s a great limitation on the number of patients.”

Dr. Rose said the number helped might be greater than previously thought, because some patients had “islands of live photoreceptors” where gene therapy might restore partial sight.

Dr. Katherine High, another study leader, who heads the Center for Cellular and Molecular Therapeutics at Children’s Hospital of Philadelphia, said that in the future, the researchers might inject 3-year-olds, and then 6-month-olds, ultimately in both eyes.

“That would give you the best chance of salvaging as much visual function as possible,” Dr. High said.

The experiment succeeded in part because the body did not mount an immune response that destroyed the invading virus. Dr. Bennett said she believed that was because “the eye itself is enclosed” and “protected from the blood supply,” so the injected compound “doesn’t escape.”

Dr. High said that, while researchers expected visual improvement to plateau after about eight weeks, “many people report continuing improvement,” suggesting their brains might be continually adjusting to the new visual pathways.

“It’s not appropriate for us to call this a cure because we don’t know how long it will last,” she said. “But it’s certainly a reversal of the blindness.”

Correction: November 7, 2009

An article on Tuesday about an experimental gene therapy procedure intended to improve vision misstated the name of a gene used in a treatment of five children and seven adults with a type of congenital retinal disease. It is RPE65, not REP65.

Correction: An earlier version of this article misstated the name of a gene involved in a study on gene therapy to improve sight. It is RPE65, not REP65.

A version of this article appears in print on November 3, 2009, on page D5 of the New York edition with the headline: Giving Sight By Therapy With Genes. Order Reprints|Today's Paper|Subscribe